PC87570 datasheet(87/168 Pages) NSC

87 / 168 page

Multi-Input Wake-Up (MIWU)

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10.3.6

Pending Register 3 (WKPND3)

The WKPND3 Register is a byte-wide, read/write register,

that latches the occurrence of a selected trigger condition

associated with the input signals WUI30 to WUI37. For a

detailed description of the register see the above descrip-

tion of the WKPND1 Register.

10.3.7

Wake-Up Enable Register 1 (WKEN1)

The WKEN1 Register is a byte-wide, read/write register,

that enables a wake-up function of the associated input sig-

nals WUI10 to WUI17. On reset, WKEN1 is cleared (0). This

disables the associated input signals.

Bits 7-0 - Wake-Up Enable (WKEN10-17)

If set (1), a valid trigger condition on the associated input

generates a wake-up signal or EXTINTx interrupt re-

quest.

If cleared (0), the associated input does not generate a

wake-up signal but may generate an interrupt request if

the corresponding MIWU output is routed to the ICU.

10.3.8

Wake-Up Enable Register 2 (WKEN2)

The WKEN2 Register is a byte-wide, read/write register,

that enables a wake-up function of the associated input sig-

nals WUI20 to WUI27. For a detailed description of the reg-

ister see the above description of the WKEN1 Register.

10.3.9

Wake-Up Enable Register 3 (WKEN3)

The WKEN3 Register is a byte-wide, read/write register,

that enables a wake-up function of the associated input sig-

nals WUI30 to WUI37. For a detailed description of the reg-

ister see the above description of the WKEN1 Register.

10.3.10 Pending Clear Register 1 (WKPCL1)

The WKPCL1 Register controls the clearing (0) of the pend-

ing bits associated with the WUI10 through WUI17 inputs.

This avoids potential hardware/software collisions during

read-modify-write operations. The register is a byte-wide

write-only register.

Bits 7-0 - Wake-Up Pending Clear (WKPCL10-17)

If any bit is set to1, the associated pending flag located in

WKPND1 is cleared (0). Writing a 0 to any bit position

leaves the value of the corresponding pending flag un-

changed.

10.3.11 Pending Clear Register 2 (WKPCL2)

The WKPCL2 Register controls the clearing (0) of the pend-

ing bits associated with the WUI20 through WUI27 inputs.

For a detailed description of the register, see the above de-

scription of the WKPCL1 Register.

10.3.12 Pending Clear Register 3 (WKPCL3)

The WKPCL3 Register controls the clearing (0) of the pend-

ing bits associated with the WUI30 through WUI37 inputs.

For a detailed description of the register, see the above de-

scription of the WKPCL1 Register.

10.4 USAGE HINTS

1. To change an edge select, perform the following steps

to avoid a pseudo wake-up condition as a result of the

edge change:

a. Clear the associated WKENx bit, followed by the

edge select change in the WKEDGx Register.

b. Clear the associated WKPDx bit, then re-enable the

associated WKENx bit.

2. The correct use of the MIWU circuit, which avoids false

triggering of a wake-up condition, requires the following

sequence of actions. Use the same procedure following

a Reset since the wake-up inputs are left floating, pro-

ducing unknown data on the MIWU input signals.

a. Clear the WKENx Register, or if used as an inter-

rupt, disable the interrupt via the ICU.

b. Write the WKEDGx Register to select the desired

type of edge sensitivity for each of the pins used.

c. Clear the WKPNDx Register to cancel any pending

bits.

d. Either set the WKENx bits associated with the pins

to be used, thus enabling them for the wake-up/in-

terrupt function, or re-enable the interrupt via the

ICU.

3. On Reset, the WKEDGx Register is configured to select

positive-going edge sensitivity for all wake-up inputs. To

change the edge sensitivity of an input signal, while

avoiding false triggering of a wake-up/interrupt condi-

tion, use the following procedure.

a. Clear the WKENx bit associated with the WUIxx in-

put to disable that input.

b. Write the WKEDGx Register to select the new type

of edge sensitivity for the specific input.

c. Clear the WKPNDx bit associated with the WUIxx in-

put.

d. Set the WKENx bit associated with the WUIxx input

to re-enable it.

WKEN17-WKEN10

WKPCL17-WKPCL10

PC87570 데이터시트(PDF) 87 Page - National Semiconductor (TI)

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